The class of polymers of carbon monoxide and olefins has been known for some time. U.S. Pat. No. 2,495,286 (Brubaker) discloses such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. 1,081,304 discloses similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium compounds as catalyst. U.S. Pat. No. 3,694,412 (Nozaki) extended the reaction to produce linear alternating polymers in the presence of arylphosphine complexes of palladium moieties and certain inert solvents.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, now becoming known as polyketones or polyketone polymers, has become of greater interest. U.S. Pat. No. 4,880,903 (VanBroekhoven et al.) discloses a linear alternating polyketone terpolymer of carbon monoxide, ethylene, and other olefinically unsaturated hydrocarbons, such as propylene. Processes for production of the polyketone polymers typically involve the use of a catalyst composition formed from a compound of a Group VIII metal selected from palladium, cobalt or nickel, the anion of a strong non-hydrohalogenic acid and a bidentate ligand of phosphorus, arsenic or antimony. U.S. Pat. No. 4,843,144 (VanBroekhoven et al.) discloses a process for preparing polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon using the preferred catalyst comprising a compound of palladium, the anion of a non-hydrohalogenic acid having a pKa of below about 6 and a bidentate ligand of phosphorous.
The resulting polymers are relatively high molecular weight materials having established utility as premium thermoplastics in the production of shaped articles, such as containers for food and drink and parts for the automotive industry, which are produced by processing the polyketone polymer according to well known methods.
Although processes for producing polyketone polymers are well known, it is also well known that polymers produced by these processes have stability problems. See for example R. Gooden, et al., Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 24, 3191-3199 (1986) and R. Gooden, et al., New Trends in the Photochemistry of Polymers, Applied Science p. 159 (1985).
These stability problems include ultraviolet (UV), melt stability, and heat aging stability, sometimes also referred to as continuous use temperature (CUT). While antioxidants and other additives provide some degree of improvement, it would be of advantage to provide new techniques and materials which yield further improvements in thermal oxidative stability of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. For most polymers including polyketones, thermal oxidative degradation leads to chain scission, reduction in moleular weight, and loss of physical properties. These adverse effects of oxidative chain scission reactions are undesirable, and continue to present a problem to those of skill in the art. Thus, there continues to exist the need to produce ethylene-CO polymers that have and exhibit superior continuous use temperature properties, and improved thermal stability.
It is a discovery of this invention that addition of suitable basic materials to polyketones leads to the formation of a thermoset thereby reducing the harmful effects of oxidative chain scission reactions and improving the thermal oxidative stability of the polyketone polymer.